Corki

Strengths

Phosphorus Bomb can be used to reveal enemy units that might be hiding in a nearby patch of brush.
Valkyrie can be used defensively as well, so try using it for a quick escape.
Corki can continue to attack while using Gatling Gun. Maximizing Gatling Gun is key to mastering Corki.

Passive · Hextech Munitions — A percentage of Corki's basic attack damage is dealt as bonus true damage.
Q · Phosphorus Bomb — Corki fires a flash bomb at a target location, dealing magic damage to enemies in the area. This attack additionally reveals units in the area for a duration.
W · Valkyrie — Corki flies a short distance, dropping bombs that create a trail of fire that damages opponents who remain in it.
E · Gatling Gun — Corki's gatling gun rapidly fires in a cone in front of him, dealing damage and reducing enemy Armor and Magic Resist.
Ultimate · Missile Barrage — Corki fires a missile toward his target location that explodes on impact, dealing damage to enemies in an area. Corki stores missiles over time, up to a maximum. Every 3rd missile fired will be a Big One, dealing extra damage.

A suggested 5-lane lineup built around Corki, based on hero partnerships and role synergy — not win rate.